Development device for electrophotography

ABSTRACT

A development device for the electrostatic photography, which comprises electroconductive electrode rollers operating as development electrodes respectively disposed movably upwardly and downwardly on a plurality of driving rollers arranged on a nearly horizontal level, and endless belt protruding from the roller surfaces and mounted on both ends of the electrode rollers so as to carry electrophotographic material held between the endless belt and driving rollers, wherein plates are provided to shield a space between the electrode rollers in contact and adjacent to the endless belt, and comprising means for supplying a liquid developer over the electrode rollers.

United States Patent 11 1 Sato et a1.

[ 1 Nov. 27, 1973 [54] DEVELOPMENT DEVICE FOR 'ELECTROPHOTQGRAPHY, p[75] Inventors: Masamichi Sato; Isoji'Takahashi, both of Asaki, Japan[73] Assignee: Fuji Photo Film Co., Ltd.,

. Kanagawa, Japan [22] Filed? Dec. 10, 1971 [21] App]. No.: 206,036

[30] Foreign Application Priority Data Dec. 10, 1970 Japan 45/109876 52us. Cl 118/637, 117/37 LE, 11 /1510. 23, 355/10 [51] Int. Cl G03g 1.3/00

[58] Field of Search ll8/DIG. 23, 637, 118/411, 259; 117/37 LE; 355/10 2[56] References Cited 3 UNITED STATES PATENTS,

3 ,601,092 8/1971 Satomi 3,301,156 1/1967 "Roeber 95/89 3,672,329 6/1972Yaman0i" 118/637 1,819,848 8/1931 Simjian .Q 118/637 X 3,556,050Trachtenberg et al. 1 18/637 1 1971 I 3,328,193 6/1967 Oliphant et a]117/37 3,330,683 7/1967 Simm et al 3,299,791 1 1967 Susumu Fukucla 95/89Primary Examiner-Mervin Stein Assistant Examiner-Leo MillsteinAttorneyGerald J. Ferguson, Jr. et al.

[5 7] ABSTRACT A development device for the electrostatic photography,which comprises electroconductive electrode rollers operating asdevelopment electrodes respectively disposed-movably upwardly anddownwardly on a plurality of driving rollers arranged on a nearlyhorizontal 1 level, and endless belt protruding from the roller surfacesand mounted on both ends of the electrode rollers so as to carryelectrophotographic material held between the endless belt and drivingrollers, wherein plates are provided to shield a space between theelectrode rollers in contact andadjacent to the endless belt, andcomprising means for supplying a liquid developer overthe electr oderollers.

' 5 Claims, 4 Drawing Figures tive paper through one or more'sets ofrollers, drive the rollers and supply developing liquid onto. the latent7 4-4 in a vessel 1 containing a developing liquid 11. The

image on the surface of the paper while the rollers are being driven.During the driving, the rollers in contact with the surface bearing thelatent'image serve as developing electrodes. I I

In accordance with one known device for the liquid development ofelectrophotogr'aphic' materials using rollers, the so called edgingeffect was avoided, i.e. it was not experienced that only the edgeportion was developed and the middle portion of the paper wasundeveloped. However, such a device has had a drawback. When thedevelopingliquid is supplied onto the electrophotographic paper, it islikely to be supplied directly or through electrode rollers onto thesurface of the paper. Accordingly, anynon-uniformity of supply of thedeveloping liquid causes irregular development directly on the image.The developing liquid supplied I flows over the electrophotographic,paper to drop through the space between the side edge of the paper andthe side plate of the rollers into a vessel 'atthe lowerpart of thedevelopment apparatus.

This flow of developing liquid results in a flow of developing liquidfrom the middle portion of the photosensitive paper ,to the edge of thepaper, resulting in streaks on the image. I

SUMMARY- OF THE INVENTION I The invention provides a liquid developingdevice which can eliminate the above described disadvantage by means ofdeveloping liquid temporarily held nearly at rest on the photosensitivefilm in the course of development. An excellent image can be obtainedhaving no developing irregularities without flow streaks due to thedevelopment liquid. v

The device according to the invention will be'described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION A PREFERREDEMBODIMENT FIGS. 1 and 2 illustrate an embodiment of the invention. Twoside plates 2 (only one side plateis shown in FIG.'2 of the drawing) areprovided which hold plural sets of rollers 3-1 and 4-1, 3-2 and 4-2, 3-4and side plate 2 can be a metal or plastic plate having vertical grooves5-1, 5-2, 5-4 holding an upper rollers 3-1, 3-4 (hereafterjcalled theelectrode rollers) acting as developing electrodes, andthe other rollers4-1, 4-4; of the roller sets can be driving rollers. Grooves 5-1, 5-4are provided topermit electrode rollers 3-1, 3-4 to move upwardly anddownwardly. The driving rollers 4-1,". 4-4 rotate in the direction ofthe arrow (driving rollers rotate at an equal speed through a drivingmeans not shown). Driving roller 4-1, 4-4 can be made of metal or analloy such asstainless steel, aluminum or 'brass, for example, with anouter diameter of 18 mm and a length of 200 mm. Electrode rollers 3-1,3-4 can have the same dimensions and be of the same material as drivingrollers 4-1, 4-4. In case of rollers 3-1, 3-4, the-diameter at Ibothend. portions 7 is 0.1 to 1 mm smaller than the outer diameter. Thelength of the smaller diameter is 5 to 20 mm.

At both end portions 7 of rollers 3-1,,. 3-4 there are mounted anendless belts 8 which is electroconductive or insulating and of aflexible character. Rollers 3-l and 3-4 at their outermost edges (asshown in FIG. 1)

serveas support rollersfor the belt 8. By friction transmit the rotationof the driving rollers to the electrode rollers 3-1, 3-4 which isthereby rotated. This endless belt 8, has a widthof 5 to 20 mm andprotrudes 0.05 2 mm from the outer diameter of the electrode roller 3 insuch manner that it depends on the end portions 7 of the rollers 3-1,3-4. Thus, the endless belt acts as spacer. Preferably, endless belt 8is made of a plastic material such .as polytetrafluoroethylene (Tradename of Du Pont: Telflon), polyethylene, polyvinyl chloride,.andpolyester, etc. Endless belt 8 rotates in close contact with side plate2. Leakage of develop-- ing liquid from the space betweenthe belt 8 andthe side plate 2 is, thus'prevented. Above the inner electrode rollers3-2 and 3-3, there are provided developing I liquid feed-pipes 9-1, 9-2carried by a support member (not shown). The developing liquid 11contained in the vessel 1 is suctioned up by a pump (not shown) intofeed pipes 9-1 and 9-2. The liquid is then supplied from aslit in pipes9-1 and 9-2 onto inner'electrode rollers upwardly so that theendlessbelt 8 contacts both sides of the paper 12. The electrophotographicpaper 12 will p I push up theelectrode rollers 3-1 the thickness of thephotosensitive paper 12. Being compressed at both .ends by the belt 8,the paper advances at the peripheral speed of the'driving rollers 44.When the forward endof the electrophotographic paper 12 is caught byroller I set 3-2 and 4-2, the developing liquid which has been suppliedfrom the slit 10-1 of the pipe 9-1 and dropping along the rotarydirection of the roller 3-2 into the vessel l is accumulated in pool.The pool. is enclosed by I the paper 12 and the endless belt '8 as thebottom and the side plate 2 and rollers 3-1 and 3-2 as walls. Thedeveloping liquid will usually leak outward partly from between theendless belt 8 and the side plate 2 and electrostatic latent imageformed on the surface of the electrophotographic paper with rollers 3-1and 3-2 serving as development electrodes.

Similarly, as the electrophotographic paper 12 advances, a pool ofdeveloping liquid is formed, respectively, between the roller 3-2 androller 3-3 and .be-

tween the roller 3-3 and roller3-4 to effect the development of theelectrostatic latent image. Upon the further advance of the paper 12 andthe separation of the rear end of the paper from the set of the rollers3-1 and 4-1, the enclosure formed by the bottom of sensitive paperopens, and thedeveloping liquid pool accumulated between rollers 3-1 and3-2 drops into the vessel 1. v

As the electrophotographic paper 12 advances, the developing liquidstored between rollers 3-2 and 3-3 I and between rollers 3-3 and 3-4will thus be consecutively delivered into the vessel 1. 1

The obtained latent image has a very good continuous gradient withoutdevelopment irregularities.

The embodiment of the invention as hereinabove described provides adevice for positive-positive development in which the toner adheres tothe area of electrostatic charge. The device can also be used forreversal development, if the driving roller 4 and side plate 2 areinsulated by bearings 6 and the electrode roller 3 and driving roller 4have applied thereto a bias voltage.

FIG. 3 is a plan view of an essential portion of another practicalembodiment of the invention. The embodiment provides the side plate 2merely for holding the rollers. This embodiment of the inventionfeatures the provision of a liquid flow preventing plate 16 (as shown inFIG. 4) between the upper rollers shown in FIG. 3. In this manner, thedimensional accuracy required for the space between side plate 2 and theelectrode roller 3 is lessened. As will be seen in FIG. '3, upperrollers 3-1 and 3-2 held in side plate 2 are provided with grooves 14 atslightly inward of their ends, the diameter of each of the grooves 14-being 0.1 1 mm smaller than the outer diameter of the rollers.Flexibleendless belt 8 is mounted on the rollers 3-1 and 3-2 inengagement with the groove 14 so as to operate as a spacer between thesurface of the latent image and the electrode rollers. On the outside ofgroove 14'there A is provided a groove 15 for holding the liquid flowpreventing plate 16.

The diameter of groove 15 is smaller than the outer diameter of roller 3by more than 1 mm and its width is slightly more than the plate 16. Theliquid preventing plate 16 is a flexible thin sheet made of metal or aplastic having a shape as shown in FIG. 4 and a thickness of 10 to 500u. The liquid preventing plate 16 is held mounted by inserting itscurved edges to thegroove 15 for shielding the side space between therollers 3-1 and 3-2. The lower. side surfaces near the linear edges ofthe liquid flow preventing plate 16 slidably contact the outer edgesides of the endless belt.

The other portions of the device have the same shape and dimensions andare of the same materials as in the device of FIGS. 1 and 2.

Similar to the preceding embodiments, the photosensitive paper, upperrollers, and liquid preventing liquid form a pool subject to only slowleakage. The developing liquid is stored in the recess formed by therollers 4 3-1 and 3-2, the liquid preventing plates ,16, the endlessbelts 8, and the electrophotographic paper. An excellent latent imagewas obtained using this combination.

The similar embodiment as shown in FIG. 3, which has liquid flowpreventing plates 16 provided at the inner edge sides of endless belt 8,was capable of providing an image of excellent quality. The liquid flowpreventing plate 16 may be provided in contact with the upper surface ofthe lower endless belt.

In accordance with this invention, the space between the endless belt,side plate, and liquid preventing flow plate has been almost eliminated.Freedom from criticality of the dimensions of the photosensitive paperandthis device were greatly increased. No significant flow of developingliquid occurred during development, so that the obtained image did nothave flow or development irregularities.

While in the embodiment of FIG. 1 four sets of rollers were used, itwill be clear that this is not a critical feature of the invention solong as the pool releasing feature is maintained. 7

Numerous modifications of the invention will become apparent to one ofordinary skill in the art upon reading the foregoing disclosure. Duringsuch a reading it will be evident that this invention provides a uniquedevelopment device for electrophotography for accomplishing the objectsand advantages herein stated.

We claim: l 1

1. A development device for the electrostatic photography, whichcomprises electroconductive electrode rollers operating as developmentelectrodes respectively disposed above a plurality of driving rollersarranged on a nearly horizontal level, an endless belt protruding fromthe roller surfaces and mounted on both ends of said electrode rollersforconveying electrophotographic material held between said endless beltand driving rollers, provided to shield a space between theelectrostatic material.

2. A development device as'in-claim 1 including means for positioningsaid electrode rollers upwardly and downwardly. l q

3. A development device as in claim 1 wherein the ends of said electroderollers and said driving rollers are joumalled in said plate. A I I 4. Adevelopment device as in claim-l including a further plate in which theends of said electrode rollers and said driving rollers are joumalled,said firstmentioned plate being supportedby said electrode rollers. v

5. A development device as in claim 4 wherein said first-mentioned plateis disposed in grooves at the ends of said electrode rollers and soshaped as to be supported by electrode rollers.

i r k

1. A development device for the electrostatic photography, whichcomprises electroconductive electrode rollers operating as developmentelectrodes respectively disposed above a plurality of driving rollersarranged on a nearly horizontal level, an endless belt protruding fromthe roller surfaces and mounted on both ends of said electrode rollersfor conveying electrophotographic material held between said endlessbelt and driving rollers, provided to shield a space between theelectrode rollers in substantial contact and adjacent to said endlessbelt, and means for supplying a liquid developer from above and oversaid electrode rollers so that a pool of said developer is formed insaid space which is bounded by said plates, said electrophotographicmaterial, said endless belts, and said electrode rollers to therebyimprove the development of said electrostatic material.
 2. A developmentdevice as in claim 1 including means for positioning said electroderollers upwardly and downwardly.
 3. A development device as in claim 1wherein the ends of said electrode rollers and said driving rollers arejournalled in said plate.
 4. A development device as in claim 1including a further plate in which the ends of said electrode rollersand said driving rollers are journalled, said first-mentioned platebeing supported by said electrode rollers.
 5. A development device as inclaim 4 wherein said first-mentioned plate is disposed in grooves at theends of said electrode rollers and so shaped as to be supported byelectrode rollers.